This invention concerns transmission of messages for network management in a telecommunication system.
In some network management systems, the network elements such as radio repeaters are connected to the network management system using a modem connection. In the context of this application, modem means an adapter used to connect a device to a transmission network. Such a system is shown in FIG. 1. The figure depicts the network management system NMS together with three radio repeaters: Repeater 1, Repeater 2, and Repeater 3. The NMS and the repeaters are connected via modems to a transmission network such as a telephone network. Through the modem connection, the network management system sends to radio repeaters configuration parameters such as the radio channels to be used, the transmission power, the phone number of the modem of the management system, etc. Correspondingly, the radio repeaters send the management system alarms indicating error situations and faults and acknowledgments of the configuration messages received from the NMS.
The establishment of a connection between the NMS and a repeater can be initiated by either the management system NMS or the repeater. The NMS initiates a connection with a repeater when it wants to change or check a configuration parameter of a repeater. In order to contact the repeater, the modem at the network management system NMS establishes a connection with the modem of the repeater via the transmission network. This connection is established when the transmission modem identifies a free modem line in the transmission network. The identifier of the modem is stored in the network management system. When the transmission network is a normal telephone network, the identification is the telephone number of the modem.
The repeaters contact the NMS to send alarms. This is done by using the identification of the modem of the management system stored by the repeater.
The modem of the network management system NMS may be busy due to an NMS initiated connection for configuring a network element. The configuration tolerates rather long delays. At the same time, another network element may try to initiate a connection with the management system in order to transmit an alarm message of high priority. This situation is shown in FIG. 2. In the figure, the arrows show attempts to establish and terminate a connection between a network management system NMS and two radio repeaters, Repeater 1 and Repeater 2, with time sequence starting from the top of the figure.
The network management system initiates a modem connection with Repeater 1 for configuration purposes (201). While the connection is still active, Repeater 2 tries to initiate a modem connection to the network management system for alarm purposes (202). The modem of the management system NMS is busy, however, and the connection can not be successfully established. Repeater 2 thus has to try to initiate the connection again (not shown in the figure). These retrials, on the other hand, reserve the modem capacity and thus increase the probability of collisions. Having transmitted all the necessary information, Repeater 1 and the network management system NMS terminate the connection, thus releasing their modems. At this stage, the modem of the network management system is no longer busy, and the connection request of Repeater 2 (205) can now be fulfilled. The alarm message and the messages triggered by the alarm message are now transmitted. The connection is terminated when all the necessary information has been transferred (206).
The problem with the prior art is the delay incurred in the transmission of messages for the management of network elements. The objective of this invention is to minimize or eliminate these problems. This objective is achieved by using the arrangement and apparatus defined in the independent claims.
The idea of this invention is to use at least two modems on the network management system side. At least one of these modems is used only for connections initialized by the network management system. At least one other modem is used only for connections initialized by any or a group of network elements controlled by the network management system.
The number of modems used for connections initiated by the management system may be more than one, thus enabling the network management system to initiate simultaneous connections to more than one network element. Likewise, more than one modem can be dedicated for connections initiated by the network elements. In such an arrangement, it is advantageous to divide the network elements into groups. The connection establishments initiated by network elements of a group are then directed to a pre-specified modem at the network management system. This can be achieved by assigning different groups of network elements identifications of different modems at the network management system.
According to another embodiment, a plurality of reception modems are used and the network elements controlled by the network management system are given sets of at least two modem identifications for the network management system. If the first dialed modem is busy when trying to establish a connection to the network management system for alarm purposes, the network element tries to establish the connection via another reception modem of the set. This embodiment may, however require some changes in the controlled network elements.
According to one preferred embodiment, at least one of the controlled network elements is a radio repeater.